21432907 has 4 divisors (see below), whose sum is σ = 21645216. Its totient is φ = 21220600.

The previous prime is 21432881. The next prime is 21432913. The reversal of 21432907 is 70923412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21432907 - 2¹¹ = 21430859 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21432967) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 106003 + ... + 106204.

It is an arithmetic number, because the mean of its divisors is an integer number (5411304).

Almost surely, 2^21432907 is an apocalyptic number.

21432907 is a deficient number, since it is larger than the sum of its proper divisors (212309).

21432907 is a wasteful number, since it uses less digits than its factorization.

21432907 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212308.

The product of its (nonzero) digits is 3024, while the sum is 28.

The square root of 21432907 is about 4629.5687704148. The cubic root of 21432907 is about 277.7753434039.

It can be divided in two parts, 2143 and 2907, that added together give a triangular number (5050 = T₁₀₀).

The spelling of 21432907 in words is "twenty-one million, four hundred thirty-two thousand, nine hundred seven".